Safety belt devices and the belt webbing provided for them in general serve the purpose of restraining the occupants in a vehicular crash in order to reduce the risk of injury to the occupants.
Thereby one of the important criteria for the impact on the occupant in a case of being restrained is what is called the chest pressure of the occupant exerted by the diagonal shoulder belt section of the belt crossing the chest of the occupant. The chest pressure is caused by the composition and area of the unit surface of the diagonal shoulder belt webbing section and the tension exerted by the diagonal webbing section, which also depends on the characteristics of the occupant and the severity of the accident. Thereby the basic parameter for reducing the chest pressure is the unit surface of the diagonal webbing section.
Since the belt webbing must be windable on a seat belt retractor of the safety belt device, for which the width of the roll box for construction reasons cannot be as wide as one would wish, the unit surface can be increased only to a limited extent. In order to overcome this disadvantage, inflatable belt webbings have already been implemented, which are made as double layers and which can be expanded by a gas generator in an early phase of the accident into a thick “sausage” with an enlarged unit surface area.
The disadvantage of this solution is that the costs of the safety belt device increase because of the gas generator that is provided, and in addition the required structural room that is needed to fasten the safety belt device is significantly increased.
Against this background, the basic task for this invention is to provide a belt webbing and a safety belt device with which the impact pressure on the occupant can be reduced with simple means while avoiding the disadvantages noted here.
To resolve the task, according to the invention a belt webbing with the features described herein is provided.
According to a feature of the invention, it is proposed that the belt webbing in a first section be set up in a longitudinal direction wider than in a second section.
Implementing the proposed solution, the impact related pressure on the occupant alone can be reduced by the form of the belt webbing using very simple means, without having additional components being provided, such as a gas generator, or providing that the belt webbing does not have to be specially woven for expansion. The position of the wider first section is thereby intentionally so chosen that when this section, with the seatbelt attached, reaches one part of the occupant, the impact related pressure on the occupant is reduced.
In addition, the solution of the task of a safety belt device with the features described herein is proposed in which according to the basic idea of the invention a belt webbing according the invention is planned, and for which a second seatbelt retractor is may be implemented on which the belt webbing can be rolled up with a second end.
Through the proposed solution, the impact related pressure on part of the occupant can be reduced, in which the first section of the belt webbing reaches the unit, whereby the second belt roller makes it possible that the belt webbing is completely rolled up exclusively with the second narrower section.
The second webbing section preferentially has a width of for example, about 46 mm to 48 mm, as is customary with standard safety belt devices. Thereby the belt webbing with the second section can be rolled up with a standard seatbelt retractor. If two seatbelt retractors are used, it is also possible to position the first section so that for a complete rolling up of the belt webbing it does not have to be rolled up on one of the seatbelt retractors, and as a result the belt webbing, despite the greater width of the first section, can always be completely rolled up, and in particular in the parked position can hang down with the smallest possible attachment to the vehicle structure.
Particularly good results in reducing the impact on the occupant can be achieved while at the same time achieving good wearing comfort, in that the first section has a width of about 75 mm to 100 mm, whereby the first section also preferentially should be about 350 mm to 600 mm long.
In addition, the belt webbing in the first section can preferentially have a 1/1 and/or a 2/2 binding, whereby the belt webbing in the wide unit section of the first section has very thick attachment points between the warp threads and the weft threads. Thereby a very even distribution of the impact over the belt webbing is achieved.
In particular a very good impact distribution can be achieved if the belt webbing in the first section has 10 to 18 weft threads/cm.
In addition, a very homogeneous impact distribution results if the belt webbing set up between the second and the first section has a transitional section with an increasing number of weft threads/cm of 6 to 18 weft threads/cm.
It is further proposed that the belt webbing between the second and the first section have a transitional section with increasing width in the direction of the first section with a length of 100 mm to 200 mm. Through the proposed transitional area and its dimensioning, the impact force distribution on the belt webbing and on the restrained occupant can be equalized, so that as a result the reduction of the occupant impact related pressure by the first section does not lead to a sudden increase of the occupant impact related pressure in the transition to the second section. It is further proposed that the belt webbing in the first section be woven in two layers lying over one another, and that the two layers be connected with one another by a binding thread. Through the proposed solution, a very smooth appearance can be achieved without visible holes. In addition, thereby the tendency to create a fold or an arch of the belt webbing in the area of the first section can be prevented.
In addition, with regard to avoiding the tendency to a fold or an arch, the seatbelt can be simply designed by having the warp threads of the belt webbing woven in at least 3 weaving beams and preferentially in 4 weaving beams. By interweaving the warp threads in different weaving beams, the belt webbing can be provided with specific features in various zones, which give specific features to the seatbelt in the horizontal direction, such as heightened stiffness.
Thereby a tendency for arching or folding can be efficiently prevented if the belt webbing is woven in a central first weaving beam with a first amount of warp threads, and with the bordering second and third weaving beams next to the central first weaving beam woven with a second number of warp threads, which is smaller than the first number of warp threads in the first weaving beam.
It is further proposed that the second and third weaving beams be formed identically and arranged to the central first weaving beam, whereby the belt webbing has identical features on both sides of the central section. Thereby there is no preferred side that tends to arch or fold up under impact. Furthermore, the belt webbing on both sides has the same features, so that the belt webbing may also lie twisted on the occupant without thereby changing the restraining characteristics.
Especially good results can be achieved with a belt webbing that in the first central weaving beam has 100 to 140 warp threads, preferentially 120 warp threads, and/or 70 to 80 warp threads in the second and third weaving beams, preferentially 75 warp threads.
It is further proposed that the binding thread be woven in a weaving beam separate from the other warp threads, whereby the binding thread can be woven intentionally with another connection other than the remaining warp threads with the weft threads. In particular it is thereby possible very simply to connect the two layers of the belt webbing with each other.
In particular a lockable belt tongue can be provided on the belt webbing that is made movable in a vehicle attachable belt lock, which divides the belt webbing into a locked position in a diagonal shoulder belt webbing section crossing the chest of an occupant and a lap belt webbing section crossing the hips of the occupant, and the first section is so dimensioned and positioned that it forms the diagonal webbing section or a portion of the diagonal webbing section. The chest pressure of the diagonal webbing section can in particular be reduced by the proposed solution. Since the hips of the occupant bear a much greater load, for reasons of a risk of injury it is unjustifiable to set the belt webbing here with a standard width; the lap belt webbing section is accordingly formed by the second narrower section of the belt webbing, and can be rolled up on the second belt roller or the first belt roller.